On a circular knitting machine, the stitch cams at each knitting station are manually adjusted for changing the length or size of the formed stitch loops. Typically, the stitch cams are adjusted by manually rotating a screw or a cam operatively connected to moveable support members on which the stitch cams are secured. In another proposed stitch cam adjustment mechanism, an automatic rotary actuator mechanism is operatively connected to the support members. The rotary actuator mechanism is adjusted for moving the support member for automatically adjusting the support member and the stitch cam secured thereto.
These mechanisms have several drawbacks. Manually adjusting a screw or cam requires a high degree of skill and the final critical adjustment relies primarily upon the skill and experience of the operator for insuring proper stitch cam height adjustment. A rotary actuator occupies the position on the knitting machine where multiple yarn feeders are normally positioned. Thus, the number of yarn feeders possible on this type of knitting machine is reduced when a rotary actuator is incorporated therein.
In one proposed knitting machine, an automatic stitch adjusting mechanism is incorporated at each yarn feeding position for adjusting the height of the stitch cam support members to a predetermined level. The mechanism includes a clutch and lever mechanism engaging a stitch cam control member for locking the control member and for controlling movement of the stitch cam support member. In this mechanism and in other manually adjustable stitch cam raising mechanisms, the stitch cams remain in a fixed position after the adjustment. During high speed knitting operation, the forces generated against the machine components as well as the generated heat and resultant thermal expansion of the machine components result in both the stitch cam height and yarn tension varying from a predetermined knitting machine operating standard. As a result, the fabric quality is lowered.